1. International Trauma Life Support
for Emergency Care Providers
CHAPTER
eighth edition
International Trauma Life Support for Emergency Care Providers, Eighth Edition
John Campbell • Alabama Chapter, American College of Emergency Physicians
Airway
Management
4
Key Lecture Points
Review anatomy.
The differences in airway management of the trauma patient as opposed to the medical patient need to be clearly emphasized. Particular emphasis needs to be placed on stabilizing the cervical spine and maintaining stability of the cervical spine during airway maneuvers.
Stress that any movement, especially hyperextension of the cervical spine during airway maneuvers, may do great damage.
Continuous monitoring of the airway is necessary to be sure it remains patent. Stress the point that suction must be immediately available.
High-flow oxygen (as close to 100 percent as possible) must be provided to trauma patients. Discuss oxygen settings.
Remind students that the oropharyngeal airway is for use only in the unconscious patient with no gag reflex.
Review airway management in the conscious versus unconscious patient.
Stress that EMTs tend to inadvertently hyperventilate patients. The starting ventilatory rate should be about 8 breaths per minute. Use of pulse oximetry and capnography is recommended.
Discuss the “BOOTS” mnemonic as a predictor of the patient who will be difficult to ventilate with a bag-valve mask.
Review management of the prone patient and the patient with profuse upper airway bleeding.
NOTE: Additional useful information can be found in:
Chapter 5: Airway Management Skills
AND
Optional Skills under Additional Resources
Optional Skill 1: Digital Intubation
Optional Skill 2: Transillumination (Lighted Stylet)
Optional Skill 3: Translaryngeal Jet Ventilation
Optional Skill 4: Pharyngotracheal Lumen Airway
Optional Skill 5: Esophageal Tracheal Combitube
Optional Skill 6: King LT-D Airway
Optional Skill 7: Laryngeal Mask Airway
Optional Skill 9: Rapid Sequence Intubation
NOTE: This lecture is designed to convey key points of Airway Management. Adjuncts will be taught in Skill Stations—do not duplicate teaching material.
Other than assessment and identification of life-threatening conditions, no skill is more important than that of airway control. Maintaining an open airway and adequate ventilation in a trauma patient can be a challenge.
Frequently are in need of immediate help
Airway control in trauma patient is rooted in several fundamental truths: Air should go in and out, oxygen is good, and blue is bad. Everything else follows from these.
IMAGE: Cutaway view of a normal, healthy human subject with nasal passages, sinuses, trachea, and lungs with bronchial tubes branching in a sectioned view of right lung and an inset showing alveolar sacs
Review basic anatomy and physiology.
Airway begins at tip of nose and lips and ends at alveolocapillary membrane, through which gas exchange takes place between air sacs of lung (the alveoli) and lung's capillary network. Airway consists of chambers and pipes, which conduct air with its 21 percent oxygen content to alveoli and carry away waste carbon dioxide that diffuses from blood into alveoli.
Nasopharynx
Nasal cavity and oropharynx are lined with moist mucous membranes that are delicate and highly vascular.
Nasal cavity divided by very vascular midline septum. Turbinates can get in way when inserting tubes.
Nasal adjuncts should go straight back, not up.
Decrease incidence of trauma through liberal lubrication of tubes and avoiding unnecessary poking about.
Oropharynx
Possible obstructions in this include teeth and tongue.
Muscles of jaw (including tongue muscle) attached to hyoid bone
Epiglottis (and other airway structures) attached to hyoid bone
Therefore, lifting jaw opens airway by lifting tongue and epiglottis.
Hypopharynx
Epiglottis is one of the main anatomic landmarks.
Epiglottis is floppy piece of cartilage covered by mucosa.
Tongue can produce some airway obstruction, but epiglottis can produce complete airway obstruction in supine unconscious patient.
Pyriform fossa on either side of epiglottis (in larynx)
Placement of an endotracheal tube here identified by “tenting” of skin on either side of superior aspect of laryngeal prominence
Thyroid cartilage easily seen in most people on anterior surface of neck as laryngeal prominence
On either side of the epiglottis is a recess called the pyriform fossa. An endotracheal tube can “catch up” in either one.
Boxlike structure shaped like a “C,” with open part of “C” representing its posterior wall, which is covered with muscle
Vocal cords are protected by thyroid cartilage.
Laryngospasm of vocal cords can produce complete airway obstruction.
Cricoid cartilage is inferior to thyroid cartilage.
Shaped like a signet ring with ring in front and signet behind
Palpated as a small bump on anterior surface of neck inferior to laryngeal prominence
Esophagus is just behind posterior wall of cricoid cartilage.
ELM External Laryngeal Manipulation—Manipulating the thyroid cartilage can help bring the vocal cords into view during endotracheal intubation. The movement is usually pressing the thyroid cartilage backward against the esophagus and then upward and slightly to the patient's right side. (Also known as the Back-up-right-pressure BURP maneuver)
Sellick maneuver pressure on cricoid at front of neck was thought to close off esophagus to pressures as high as 100 cm H2O and was believed to decrease incidence of vomiting and gastric distention.
Recent studies question the efficacy of the Sellick maneuver in preventing aspiration of stomach contents.
SHOULD NOT BE USED!
Cricothyroid membrane
Connects inferior border of thyroid cartilage with superior aspect of cricoid
Find most prominent part of thyroid cartilage and then slide index finger down until you feel a second “bump” just before your finger palpates last depression before sternal notch.
That second bump is cricoid cartilage, and at upper edge of this is cricothyroid membrane.
Sternal notch
Palpated at the junction of the clavicles with the upper edge of the sternum
ET tube cuff should lie at this point when properly placed.
In patients with a thick neck, you may find cricoid cartilage more easily by going from sternal notch upward until you feel first prominent cartilage “bump.” Just over “top” of this bump is cricothyroid membrane.
Tracheal rings
C-shaped cartilaginous supports for trachea continue beyond cricoid cartilage.
Trachea divides at carina into left and right mainstem bronchi.
Note right mainstem bronchus takes off at angle slightly more in line with trachea.
As a result, tubes or other foreign bodies usually end up in right mainstem bronchus.
One goal of properly performed endotracheal intubation is to avoid a right (or left) mainstem bronchus intubation.
Lungs
Organs through which gas exchange takes place
Contained within and usually fill up “cage” formed by ribs
NOTE: Point out vessels underneath ribs on smaller image. For decompression, insert needle over rib to avoid artery.
Pleural space
Potential space between internal chest wall and lung surface
Glottic opening
Only opening to outside from lungs
Between vocal cords
Expansion of chest wall and movement of diaphragm downward cause lungs to expand; air rushes in through glottis.
Alveolocapillary membrane
Air travels down smaller and smaller tubes to alveoli, where gas exchange (respiration) takes place (on-loading of oxygen and off-loading of carbon dioxide).
Emphasize these are for the AVERAGE adult—not absolute.
15 centimeters from teeth to vocal cords
20 centimeters from teeth to sternal notch
25 centimeters from teeth to carina
Note distance ET tube inserted:
To be sure it is not in too far.
To be sure it does not change with patient movement.
Secure head down to guard against movement.
Will lessen risk of tube displacement
Will reduce trauma to tracheal mucosa
Will result in less stimulation to airway reflexes
Reflexes attempt to expel any offending foreign material from oropharynx, glottic opening, or trachea.
Well supplied by sensitive nerves that can activate swallowing, gag, and cough reflexes
Activation of these reflexes by stimulation of upper airway can cause significant cardiovascular stimulation as well as elevation in intracranial pressure.
Consider use of topical lidocaine (see Chapter 5).
Careful observation required to identify easily displaced ET tube
Oxygen saturation and end-tidal CO2 monitoring assist greatly.
In the absence of the need to control “major bleeding,” the first essential maneuver is ensuring a patent or open airway.
Must be done quickly because patients cannot tolerate hypoxia for more than a few minutes
Ensuring an open airway in trauma can be a challenge.
Trauma can disrupt anatomy; bleeding can lead to airflow obstruction and obscure airway landmarks.
Always consider possibility of cervical-spine injury.
Some airway maneuvers, including suction and insertion of nasopharyngeal and oropharyngeal airways, may stimulate a patient's protective reflexes and increase likelihood of vomiting and aspiration, cardiovascular stimulation, and increased intracranial pressure.
NOTE: These are all essential for maintaining patent airway and will be taught in skill station.
Constantly observe for airway problems.
One team member must be responsible for both airway control and adequate ventilation for any patient who might be at risk of airway compromise.
Many patients have full stomachs, are anxious, and prone to vomiting.
Some patients will be bleeding into their oropharynx and swallowing blood.
Always immediately clear blood and secretions.
Anticipate vomiting and aspiration.
Method of intubation should be suited to each patient.
Low risk of cervical-spine injury can be intubated with direct-vision orotracheal intubation.
Some evidence exists that direct-vision orotracheal intubation results in movement of head and neck, which leads to question as to whether use of this method presents an added risk in possible cervical-spine injuries. Controversy exists as to whether such movement is either substantial or of real clinical significance.
Intubation by nasotracheal route, tactile or transillumination methods, or a combination of two should be reserved for patients with specific indication for alternative techniques.
Monitor endotracheal tube position by pulse oximetry and continuous expiratory CO2 monitoring.
Upper airway noises include snoring, gurgling, stridor (and silence).
Stridor or an inability to achieve chest rise with positive-pressure ventilation are indications for early endotracheal intubation.
Constantly observe for respiratory problems.
Assess rate of respirations and note any complaints or issues.
Spontaneously breathing patients should be assessed for adequate tidal volume.
Bear the chest to at least below the breast to observe adequate chest rise and fall.
Ensure oxygen is being delivered as necessary to maintain normoxia (>90%).
Noisy breathing is obstructed breathing.
Monitor lung compliance if ETT in place.
Monitor pulse oximetry and end tidal CO2 (recommended in all trauma patients).
Development of confusion or combativeness can be signs of hypoxia.
Patient may need airway procedure.
If intubated, ETT may no longer be properly located (displaced).
Consider combative patients hypoxic until systematic evaluation rules it out.
Patients with spinal motion restriction (SMR) are high risk for aspiration and airway compromise.
The greatest threat to the patient’s airway is vomitus and aspiration.
Airway management takes precedence over securing to backboard.
Portable suction devices are essential equipment and should be kept with the oxygen supplies so they are an integral part of the kit and not an “extra” piece of equipment requiring extra hands.
Portable suction devices should be powered by batteries and/or hand powered (making sure to have hand power as a backup if batteries die).
Suction unit should be capable of suctioning blood clots, thick secretions, and food from the oropharynx.
Suction unit should accommodate larger (0.8–1.0 cm) tubing to handle whatever material is suctioned from the patient.
In some cases, the ETT can be used to withdraw blood or gastric contents.
NPA
Keeps tongue off posterior pharyngeal wall
Good for patients with gag reflex in place
May cause some damage/bleeding
Insert straight back, not upward.
In a pinch, a 6-6.5mm ETT may be used in place of NPA.
Measure from angle of jaw to tip of nose and add 1 cm.
Remove adapter, cut tube to length, replace adapter to act as “flange.”
Use a lot of lubrication.
Insert into nare.
Do not inflate cuff if cuff is present.
Keeps tongue off posterior pharyngeal wall
Patient must not have intact gag reflex.
Use as bridge device before insertion of more advanced airway.
If patient accepts an OPA, he/she has lost protective reflexes and requires a more advanced airway.
S.A.L.T.
Not only an OPA, but also serves as guide to insert an ETT and acts as holder and protector
BIADs
May be inserted without visualization of the larynx
Not as effective as ETT in preventing aspiration but provide effective ventilation and oxygenation
Easier and faster to insert
Now the recommended initial airways are recommended for medical cardiac arrest by AHA/ILCOR.
In many areas, these are basic level skills.
Evidence suggests single tube devices such as King LT-D™ and the LMA™ may be best suited for prehospital than the multi-tube Combitube®.
ETT
Gold standard of airway care for patients unable to protect their airway or needing assistance breathing
Not always most appropriate choice in pre-hospital
ETT in trauma patients
Circumstances are less than optimal.
Gag reflex may be intact.
Spinal motion restriction may be needed.
Reduces movement making visualization of airway difficult
Remove front or entire C-Collar to make intubation easier.
Note: Alternatives to intubation should be covered in the airway skill station.
Appropriate decision regarding whom and how to intubate will ultimately be related to several factors.
Assessment of patient and particular clinical presentation, skill set of individual health-care professionals present, and EMS system
Time is also a factor unique to prehospital setting.
BVM ventilation and immediate transport of patient may be a better option in certain instances than taking additional time required to perform RSI.
Rapid sequence intubation (RSI)
Use of paralytic agents to quickly facilitate tube placement and to minimize risk of aspiration
Be aware: Deep sedation and RSI inhibit normal muscle tone of airway and thus may make it impossible to effectively mask-ventilate patient.
It is necessary to immediately place an endotracheal tube to achieve successful ventilation.
Must be very familiar with predictors of difficult laryngoscopy and intubation before deciding to intubate a patient who is already breathing on his own
Remember, patients who have spontaneous yet inadequate respiratory effort are better off than a patient who has been given a paralytic and can neither be mask-ventilated nor intubated.
“MMAP” airway to assess difficulty prior to sedation for intubation
Proposed to identify certain physical features that predict potentially difficult laryngoscopy and intubation
Mallampati
Measurement 3-3-1
Atlanto-occipital extension
Pathology
NOTE: Table 4-1: Estimating Difficulty of Intubation.
NOTE: This image has a Mallampati score of II.
M—Mallampati Score
Score ranges from I to IV, dependent on what structures can be viewed when mouth is opened (Table 4-1).
Predicts difficulty of manipulation of tongue for visualization (whether tongue will obstruct view)
Higher grade is more difficult to intubate.
I Entire tonsil or tonsillar bed visible
II Upper half of tonsil or tonsillar bed visible
III Soft and hard palate clearly visible
IV Only hard palate visible
M—Measurement 3-3-1
Measurement of movement of structures
Predicts difficulty of manipulation of jaw for visualization (whether structures will line up for good visualization)
3 Should be able to fit three (3) fingers under chin between hyoid bone and mentum of chin (hyomental distance)
3 Should be able to open mouth so that three (3) fingers fit between upper and lower incisors (mouth opening)
1 Should be able to protrude lower jaw such that lower teeth are 1 cm (1) beyond upper teeth (anterior jaw subluxation)
NOTE: Some references also include:
2 Should be able to fit two (2) fingers between thyroid notch and floor of mandible (top of neck)
A—Atlanto-occipital extension
AKA atlanto-occipital joint extension; chapter also refers to atlanto-occipital junction
Measurement of head and neck mobility
If cervical-spine injury is not suspected, predicts ability to extend head at atlanto-occipital junction to achieve “sniffing position”
P—Pathology (or pathological obstructing conditions)
Any clinical evidence of anatomic airway obstruction
Airway obstruction can result from medical or traumatic conditions, such as edema, infection, burns, penetrating or blunt injuries.
This is particularly important, as upper airway obstructive pathology is a relative contraindication to RSI.
Oxygenation is NOT ventilation. Normal perfusion will allow efficient on-loading of oxygen into blood at alveolocapillary membrane and result in a blood arterial oxygen level of around 100 mmHg (measured by arterial blood gas; this is abbreviated PaO2).
Pulse oximetry is measurement of arterial oxygen saturation in peripheral circulation, which is displayed in a percentage value (% SpO2).
Goal: Maintain SpO2 at 95% or higher.
SpO2 >95% with signs and symptoms of hypoxia or difficulty breathing
Administer oxygen.
In other words, do not withhold oxygen when it is needed, even though SpO2 may be greater than 95%.
SpO2 <92% usually cause for concern
Requires intervention, such as opening airway, suction, oxygen, assisted ventilation, intubation, decompression of tension pneumothorax
SpO2 <90% is critical and requires immediate intervention to maintain adequate tissue oxygenation.
Recommended for use on all trauma patients
Should be used on all patients with any type of respiratory compromise
NOTE: Nasal cannula commonly considered to deliver a concentration of 25–45% at 2–6 liters per minute (lpm)
Patients who are injured need supplemental oxygen, especially if unconscious, have altered mental status, respiratory distress, signs of poor perfusion, or are pregnant.
Supplemental oxygen must be used to ensure adequate oxygenation when you perform positive pressure ventilation.
Oxygenation supplemented during mouth-to-mask ventilation by running oxygen at 10–12 liters per minute through oxygen nipple attached to most masks or by placing oxygen tubing under mask and running it at same rate
Flow-restricted oxygen-powered ventilation devices (FROPVD) will provide 100% oxygen at a flow rate of 40 liters per minute at a maximum pressure of 50 cm ± 5 cm water.
Translaryngeal jet ventilation (TLJV) can provide a quick, reliable, and relatively safe temporary method of adequate oxygenation and ventilation when airway cannot be maintained because of obstruction or partial obstruction above cords, and access below level of cords is needed. A special cannula is inserted through cricothyroid membrane, and patient is ventilated using a special manual jet ventilator device. (See Appendix A: Optional Skill 3: Translaryngeal Jet Ventilation.)
Emphasize that ventilation is movement of air or gases in and out of lungs.
At rest, adults normally take in about 400 to 600 cc with each breath, which is tidal volume.
Minute volume is amount of air moved in and out each minute.
This is an important value and is normally 5–12 liters per minute since volume of air moved through lungs (across alveolocapillary membranes) is directly related to off-loading of carbon dioxide from blood.
Airway dead air space is approximately 150cc for the adult 70 kg patient. Thus, a tidal volume of 250cc is much different than a tidal volume of 750 cc(100cc vs. 600cc available to alveoli).
Tachypnea and bradypnea do not indicate amount of air moved through lungs (as exemplified on next slide).
Tachypnea is an increased rate of respiration.
Bradypnea is a decreased rate of respiration.
NOTE: This point sets up next slide, which distinguishes that tachypnea and bradypnea are not same as hyperventilation and hypoventilation.
Ventilation is movement of air in and out of lungs. Normal ventilation will allow efficient off-loading of carbon dioxide from blood at alveolocapillary membrane and result in blood pCO2 of 35–40 mmHg for all age groups and nondiseased lungs.
pCO2 level in COPD is higher.
Hyperventilation and hypoventilation do NOT refer to oxygenation or respiratory rate. They refer to amount of carbon dioxide retained in blood.
Hypoventilation or decreased movement of air is shown by carbon dioxide retention in blood (pCO2 > 40 mmHg). Hypoventilation causes retention of carbon dioxide and drives pCO2 to above 40 mmHg (hypercapnia).
Hyperventilation or increased movement of air is shown by blowing off carbon dioxide (pCO2 <35 mmHg). Hyperventilation causes increased removal of carbon dioxide and drives pCO2 to below 35 mmHg (hypocapnia).
Ventilation is NOT oxygenation. Oxygenation is on-loading of oxygen to red blood cells at alveoli. Sufficient concentration of oxygen must be available at alveolocapillary membrane to transfer into blood. Carbon dioxide diffuses across alveolocapillary membrane more readily than oxygen, so it is easier to off-load carbon dioxide from blood than it is to on-load oxygen to blood.
If lungs are injured, oxygen on-loading may be inhibited. However, carbon dioxide is still off-loaded by ventilation. Therefore, cells can be hypoxic while having normal carbon dioxide levels in blood.
A patient with a respiratory rate of 36, an end-tidal carbon dioxide level (ETCO2) of 30 mmHg, and an oxygen level of only 80 mmHg does not need to breathe faster (hyperventilate); he needs to have supplemental oxygen.
Capnography is a direct measurement of ventilation in lungs. End-tidal carbon dioxide (ETCO2) reflects CO2 concentration off-loaded at alveolocapillary membrane at end of tidal volume.
End-tidal CO2 relates directly to pCO2, but is not same as pCO2 .
ETCO2 is usually 2–5 mmHg lower than pCO2 resulting in ETCO2 of around 35–40 mmHg. (Some sources say 30–43 mmHg can be considered normal.)
Goal: Maintain ETCO2 of 35 mmHg.
Capnography also indirectly measures metabolism and circulation.
Before exhalation, blood carries CO2 from cells to lungs. The rate and amount of CO2 that reaches lungs depends on cardiac output.
In patients with normal cardiac function, normal CO2 levels will reach lungs, and ETCO2 will be normal.
In patients with poor cardiac function, low levels of CO2 will be transported to lung, and ETCO2 will be low.
When in doubt, give oxygen!
Remember, ventilation rate is NOT same as hyperventilation and hypoventilation.
Ventilation rates should be adjusted to maintain appropriate ETCO2.
Only a head-injured patient with evidence of herniation and no or minimal response will indicate need for hyperventilation.
Hyperventilation is ONLY recommended for use in treating patient with signs of cerebral herniation after correcting hypotension and/or hypoxia.
Rate of 20 for adults, 25 for children, and 30 for infants
If capnography available, ETCO2 level at about 25 mmHg during hyperventilation
NOTE: More about this in Head Trauma lesson
Monitor lung compliance and search for cause of any change in compliance.
NOTE: % SpO2 = pulse oximetry = oxygen saturation in peripheral circulation
NOTE: ETCO2 = end-tidal CO2 = CO2 in expired air = capnography/capnometry
Pulse oximetry
Measurement of arterial oxygen saturation in peripheral circulation displayed in a percentage value (% SpO2)
Should be used on all patients with any type of respiratory compromise
Goal: Maintain SpO2 at 95% or higher.
SpO2 >95% with signs and symptoms of hypoxia or difficulty breathing
Administer oxygen.
SpO2 <92% usually cause for concern
Requires intervention (opening airway, suction, oxygen, assisted ventilation, intubation, decompression of tension pneumothorax)
SpO2 <90% is critical and requires immediate intervention to maintain adequate tissue oxygenation.
Carbon dioxide monitoring
Simple detection of end-tidal CO2 (ETCO2)
Colorimetric or qualitative capnometry
Detects ETCO2 only; does not monitor
Does not accurately measure amount of CO2
Quantitative capnometry
Detect and measure ETCO2 without a waveform.
Monitor adequacy of ventilations and accurately “titrate” ETCO2 levels where pCO2 levels are critical, such as those with closed head injuries.
Quantitative waveform capnography
Detect and measure ETCO2 with diagnostic waveform.
Waveforms appear within 2 seconds of actual breath.
Continuously monitor waveform and value.
Uses:
Confirm (by shape of waveform) endotracheal placement even in low perfusion states.
Perfusion monitor, airway monitor, ventilation monitor
Capnography is strongly recommended in all intubated patients, and pulse oximetry is recommended in all trauma patients.
Pulse oximetry and end-tidal CO2 monitoring are most reliable methods of monitoring effectiveness of positive-pressure ventilation.
Pulse oximetry measures oxygen saturation of blood, and capnography measures CO2 level of exhalation not carbon dioxide level in blood (pCO2).
Use ETCO2 level to judge whether to increase or decrease rate of ventilation.
Adjust ventilation rate to keep ETCO2 between 35–40 mmHg.
Intermittent positive pressure ventilation (IPPV)
Everything from mouth to mouth to bag mask to ETT.
Esophagus takes 25cm H2O pressure to allow gastric insufflation.
BVM and FROPVD can produce 25cm plus, especially if squeezed rapidly and forcefully.
BVM can generate >60cm H2O.
FROPVD generates 50cm H2O.
Know the approximate delivered volume to reduce over inflation which would result in insufflation.
Adult BVM holds approximately 1800 cc.
At best, 1200 cc delivered with 1 hand by an adult
Average is 800-1000 cc.
FROPVD delivers approximately 700cc/second.
Average adult tidal volume is 500 cc.
NOTE: Mask seal and BVM ventilation will be covered in Skill Stations.
Effective BVM ventilation requires a high degree of skill.
Predictors of difficult BVM ventilation using “BOOTS” mnemonic.
Facial hair (beards) and lack of teeth (toothlessness) make mask seal more difficult.
Obesity increases both lung and chest compliance.
In older patients (and in those in whom cervical-spine control is essential), it is more difficult to get proper head and neck positioning.
Snoring or stridor indicate presence of airway obstruction.
If BVM ventilation is not effective:
Reposition airway and use an OPA or NPA.
If still ineffective, initiate two-person BVM ventilation with extra emphasis on jaw-thrust maneuver to maximize airway opening.
Reevaluate for airway obstruction.
No obstruction and continued ineffective ventilation: Place a BIAD (blind insertion airway device) or endotracheal tube to definitively ventilate (Figure 4-14).
The elasticity of the lungs and chest will influence the ease of breathing.
Normal elasticity will allow air to enter the glottic opening with little gastric distention.
Poor elasticity will cause more difficult ventilation and likely increase gastric distention.
Compliance
Ability of lungs and chest wall to expand and ventilate
“Good compliance”
“Bad/poor compliance”
IMAGE: Airway Kit
Airway equipment must be in good working order and immediately available.
Contents of airway kit should be checked each shift.
Some kits may have other advanced equipment such as translaryngeal jet ventilation (TLJV) or flow-restricted oxygen-powered ventilation devices (FROPVD).
Trauma patients provide greatest challenge in airway management.
